About 3.5 Million Years Ago, a Stream of Gas Outside the Milky Way Would Have Lit Up the Night Sky

It’s a truism to point out that modern humans have only been around for the blink of an eye, relative to the age of the Universe. But the Universe was an active place long before we were around to observe all of that activity. And about 3.5 million years ago, it’s possible—if only remotely—that our ancient ancestors noticed something change in the night sky.

Would it have stirred something inside them? Impossible to know.

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A Star is Orbiting the Milky Way’s Black Hole and Moving Exactly How Einstein Predicted it Should

At the center of our galaxy, roughly 26,000 light-years from Earth, is the Supermassive Black Hole (SMBH) known as Sagittarius A*. The powerful gravity of this object and the dense cluster of stars around it provide astronomers with a unique environment for testing physics under the most extreme conditions. In particular, it offers them a chance to test Einstein’s Theory of General Relativity (GR).

For example, in the past thirty years, astronomers have been observing a star in the vicinity of Sagittarius A* (S2) to see if its orbit conforms to what is predicted by General Relativity. Recent observations made with the ESO’s Very Large Telescope (VLT) have completed an observation campaign that confirmed that the star’s orbit is rosette-shaped, once again proving that Einstein theory was right on the money!

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SETI Researchers Release Petabytes of Data in the Search For Aliens

Last week (Friday. Feb. 14th), the Breakthrough Listen Initiative released about 2 petabytes of optical and radio data that they have accumulated over the past four years. This is the second data release by the non-profit effort (as part of Breakthrough Initiatives) and the public is once again invited to search through the data for possible signs of extraterrestrial communications.

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More Mysterious Space Blobs Have Been Found Near the Center of the Milky Way

At the center of our galaxy lies a region where roughly 10 million stars are packed into just 1 parsec (3.25 light-years) of space. At the center of this lies the supermassive black hole (SMBH) known as Sagittarius A*, which has a mass of over 4 million Suns. For decades, astronomers have been trying to get a better look at this region in the hopes of understanding the incredible forces at work and how they have affected the evolution of our galaxy.

What they’ve found includes a series of stars that orbit very closely to Sagittarius A* (like S1 and S2), which have been used to test Einstein’s Theory of General Relativity. And recently, a team from UCLA’s Galactic Center Orbits Initiative detected a series of compact objects that also orbit the SMBH. These objects look like clouds of gas but behave like stars, depending on how close they are in their orbits to Sagittarius A*.

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Milky Way’s Black Hole Just Flared, Growing 75 Times as Bright for a Few Hours

Illustration of the supermassive black hole at the center of the Milky Way. Credit: NRAO/AUI/NSF

Even though the black hole at the center of the Milky Way is a monster, it’s still rather quiet. Called Sagittarius A*, it’s about 4.6 million times more massive than our Sun. Usually, it’s a brooding behemoth. But scientists observing Sgr. A* with the Keck Telescope just watched as its brightness bloomed to over 75 times normal for a few hours.

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There’s a Ring of Cool Gas Wrapped Around the Milky Way’s Supermassive Black Hole

There’s a lot going on at the center of our galaxy. A supermassive black hole named Sagittarius A-Star resides there, drawing material in with its inexorable gravitational attraction. In that mind-bending neighbourhood, where the laws of physics are stretched beyond comprehension, astronomers have detected a ring of cool gas.

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This Star has been Kicked Out of the Milky Way. It Knows What It Did.

Researchers from the University of Michigan confirm that a runaway star was ejected from the Milky Way's disk rather than the galactic core. Image Credit: Kohei Hattori

Every once in a while, the Milky Way ejects a star. The evicted star is typically ejected from the chaotic area at the center of the galaxy, where our Super Massive Black Hole (SMBH) lives. But at least one of them was ejected from the comparatively calm galactic disk, a discovery that has astronomers rethinking this whole star ejection phenomenon.

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One of Our Best Views of the Supermassive Black Hole at the Heart of the Milky Way

Top left: simulation of Sgr A* at 86 GHz without interstellar scattering. Top right: simulation with interstellar scattering. Bottom right: observed image of Sgr A*. Bottom left: observed image of Sgr A* after removing the effects of interstellar scattering. Credit: S. Issaoun, M. Mo?cibrodzka, Radboud University/ M. D. Johnson, CfA

An almost unimaginably enormous black hole is situated at the heart of the Milky Way. It’s called a Supermassive Black Hole (SMBH), and astronomers think that almost all massive galaxies have one at their center. But of course, nobody’s ever seen one (sort of, more on that later): It’s all based on evidence other than direct observation.

The Milky Way’s SMBH is called Sagittarius A* (Sgr. A*) and it’s about 4 million times more massive than the Sun. Scientists know it’s there because we can observe the effect it has on matter that gets too close to it. Now, we have one of our best views yet of Sgr. A*, thanks to a team of scientists using a technique called interferometry.

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Astronomers Get as Close as They Can to Seeing the Black Hole at the Heart of the Milky Way

Since the 1970s, astronomers have theorized that at the center of our galaxy,  about 26,000 light-years from Earth, there exists a supermassive black hole (SMBH) known as Sagittarius A*. Measuring an estimated 44 million km (27.3 million mi) in diameter and weighing in at roughly 4 million Solar masses, this black hole is believed to have had a profound influence on the formation and evolution of our galaxy.

And yet, scientists have never been able to see it directly and its existence has only been inferred from the effect it has on the stars and material surrounding it. However, new observations conducted by the GRAVITY collaboration** has managed to yield the most detailed observations to date of the matter surrounding Sagittarius A*, which is the strongest evidence yet that a black hole exists at the center of the Milky Way. Continue reading “Astronomers Get as Close as They Can to Seeing the Black Hole at the Heart of the Milky Way”